Ultrasound, pH, and Magnetically Responsive Crown-Ether-Coated Core/Shell Nanoparticles as Drug Encapsulation and Release Systems

Abstract

Core@shell nanoparticles with superparamagnetic iron oxide core, mesoporous silica shell, and crown ether periphery were fabricated toward drug delivery and tumor cell imaging. By the concept of nanovalve based on supramolecular gatekeeper, stimuli-responsive drug delivery nanosystems Fe3O4@SiO2@meso-SiO2@crown ethers were synthesized by (i) modified solvothermal reaction; (ii) sol-gel reaction; and (iii) amide coupling reaction. The successful coupling of the dibenzo-crown ethers onto the mesoporous silica shell was confirmed by thermogravimetric analysis and Infrared spectroscopy. In this system, the "ON/OFF" switching of the gatekeeper supramolecules can be controlled by pH-sensitive intramolecular hydrogen bonding or electrostatic interaction (such as metal chelating). Biological evaluation of the nanoparticles renders them noncytotoxic and can be uptaken by L929 cells. In this work, the antitumor drug (doxorubicin) loading and release profiles which were studied by the UV/visible absorption spectroscopy. The mechanism involves the best-fit binding of crown ethers with cesium or sodium ions at different pH values with ultrasonic wave in phosphate buffered saline (PBS). Magnetic resonance imaging analysis of the particles reveals a high relaxivity, rendering them potentially useful theranostic agents.

Core–shell designed scaffolds for drug delivery and tissue engineering

“…In particular, the rupture mechanism is often designed to be stimuli-dependent, in such a way that it is responsive to temperature, pH, or enzyme [87][88] (as presented in Fig. 6c).…”

Development and Characterization of Stimulus-Sensitive Nano/Microparticles for Medical Applications

“…At pH 4 and on application of ultrasound, a significantly higher amount of doxorubicin was released from these biocompatible NPs. This occurs because ultrasound application at low pH triggers breaking down of electrostatic interactions between crown ether's ethylene glycol chains and the Na + ions, followed by dissociation of the ions and subsequent leakage of the drug molecules [134].…”

Fe3O4@ZnS@Glycine nanoparticle as a novel microwave stimulus controlled drug release system

“…The bands at 2923 and 2840 cm -1 are assigned to the stretching C-H vibrations of alkyl, and the band at 1623 cm -1 is assigned to the stretching N-H vibrations [14]. The band at 1445 cm -1 corresponds to asymmetric stretching vibration of -COO -, and the band at 1077 cm -1 comes from C-O stretching vibrations [13,14], confirming the glycine moieties binding to the surfaces of Fe 3 O 4 @ZnS nanoparticles. The FTIR spectrum of Fe 3 O 4 @ZnS@Glycine-VP16 (Fig.…”

“…Yuan et al [12] developed a chemotherapeutic drug doxorubicin and photo-thermal conjugated polymer co-loaded nanoplatform using a near-infrared laser responsive amphiphilic brush copolymer as the encapsulation matrix, which can efficiently convert laser energy into thermal energy for release of the attached drugs and photo-thermal therapy. However, the use of light and alternating magnetic fields shallow tissue penetration and difficulty controlling the temperature [13,14]. Microwave irradiation provides better thermal efficiency, high tissue penetration depth (10-15 cm) and accurate control by varying parameters such as the power and duration of the irradiation [8,15].…”